Isn't this literally Arma3Server what you're asking for? In steam, click on Library -> Tools then find Arma 3 Server. Download, run, and enjoy. (PS. Use TADST)

@chose

That's a good workaround, but I'm not really satisfied with it. I think for just a single unit, the formation direction should be his absolute direction.

Anyway, I'm using this workaround with usually a high degree of success.
_this addAction ["Speak To",
{
_vd = (getPosASL (_this select 1)) vectorDiff (getPosASL (_this select 0));
_dir = (_vd select 0) atan2 (_vd select 1);
if (_dir < 0) then {_dir = 360 + _dir};
hint str ((direction (_this select 0)) - _dir);
if (((direction (_this select 0)) - _dir) > 0) then
{

		(_this select 0) setFormDir (_dir - 30);

}else
{

		(_this select 0) setFormDir (_dir + 30);

};
}, [], 6, false];
This also solves the problem of units not turning AT ALL if the new direction is less than 30 degrees by offsetting the new direction by 30 degrees.

I agree, KK. The worst part of it is that you can use setDir to turn the units, but it doesn't look fluid at all, and the unit will attempt to turn back to his original azimuth for some reason. So having the units not turn all the way is a big problem. I also saw that if the new bearing is within 30 degrees of the original, the unit just won't even turn at all, I think it has a 100% reproduction rate.

I think somebody wasn't paying enough attention in trigonometry class when they coded this command :P

1 year later. Any news yet?

Any news on this?

Excellent, thanks for the heads up, KK. Hopefully it's not too far down the list

I've researched the issue further and saw that numbers have plenty of accuracy, but when you try to show them with a hint or if you create a variable and save them, that's when you begin to lose accuracy due to rounding.

I'm going to rewrite the function I posted in my post on the BIS forum, so it doesn't rely on an actual object.